1. Field of the Invention
The invention relates to a valve mechanism for controlling the motions of a piston relative to a cylinder, wherein the piston is not connected to any crankshaft or similar device for limiting the extreme displacements of the piston relative to the cylinder.
2. History of the Prior Art
There are a large number of piston-cylinder arrangements disclosed in the prior art wherein the piston is not connected to a crankshaft which accurately controls the extreme positions of the piston relative to the cylinder. In such apparatus, it is necessary to control the operation of inlet and exhaust valves in the cylinder head so that the exhaust valve is open as the piston approaches the cylinder head, thus offering minimum resistance to the piston movement, but is closed prior to the piston reaching the cylinder head so as to provide a cushion of gas to arrest the movement of the piston without damaging the cylinder head. The same mechanism requires a special inlet valve, which is closed while the piston is remote from the cylinder head but is opened to introduce pressured gas into the cylinder as the piston is brought to a stop adjacent the cylinder head. See, for example, the valving construction disclosed and claimed in co-pending application Ser. No. 617,288 filed June 4, 1984 and assigned to the Assignee of the Instant Application. The prior art valving mechanisms for such piston-cylinder mechanisms have not been entirely reliable in their performance.